Systems for defrosting frozen food items are known. These involve blowing heated air over frozen food until it reaches a desired defrosted temperature. However, for food items which are not evenly shaped, for example those having one part notably thinner than another part, the known methods can lead to overheating of the thinner part and an incomplete defrost of the thicker part. Spoiling of the food item can thus occur. This may lead to bacterial growth, may render the food item unsuitable for human consumption, and may spoil the quality of the food item which could reduce its sale price and affect its taste.
Such problems are particularly noticeable when defrosting fish. In particular, tuna is sensitive to spoiling when being defrosted. For example, a frozen loin of tuna requires care to defrost as often one end of a loin is significantly thicker than the other end; thus it is difficult to defrost the loin evenly, without spoiling. Moreover, tuna flesh is more sensitive to spoiling than other fish. Firstly, there is a risk of histamines forming in the flesh if overheating of the flesh occurs. Secondly, the high concentration of haemoglobin in tuna flesh means the flesh can quickly deteriorate if overheated, which degrades the quality of the texture and colour of the tuna flesh.
It is desirable to provide an improved method of defrosting a food item, which is suitable for defrosting of tuna.